It is conventionally known in the field of photography to use a contained single bi-directional motor for winding and rewinding photographic film in a 35 mm camera. For example, in commonly assigned U.S. Pat. No. 5,323,197, an associated gear train attached to the output pinion of the bi-directional motor interconnects the film cartridge spool and the take up spindle to cause film to either be pulled from the cartridge and onto the take-up spool, or to be rewound into the confines of the cartridge. The gear train includes a single swing gear which is selectively engageable with the film cassette spool to allow film rewinding depending on the direction of the motor.
With the advent of so-called "thrust" type film cartridges, such as those described in U.S. Pat. Nos. 5,359,378, 5,248,108, and 5,031,855, among others, film transport systems have been provided which allow film to be initially driven or thrust from the interior of the cartridge for winding of the film onto the take-up spool, rather than requiring a user or manufacturer to first cinch an extending leader portion of the filmstrip onto the takeup spool before energizing the bi-directional motor to wind the film. In U.S. application Ser. No. 07/678,216, a gear train includes a pair of movable gears which are separately engageable with the film cartridge spool to allow film to be thrust from the cartridge and onto the take-up spool, or to allow film to be rewound. The gears are each in rotational contact with a driving gear and are connected to each other by means of an extension arm. This arm is pivotable to allow one of the swing gears to engage the film cartridge spool when the output pinion of the motor is rotated in a film advancing direction, thereby creating the thrust mode, and the other swing gear to engage the film cartridge spool when the output pinion is rotated in a film rewinding direction, allowing film rewinding. Additional parts, particularly the pivotable extension arm, must be added to the camera, adding increased cost and size thereto, and in which savings in cost and material are always desirable.